Abstract

In situ, high-temperature energy-dispersive X-ray powder diffraction (EDXRD) data have been
collected on synthetic and a natural sample of mercury sulphide (HgS). These measurements were
made between temperatures of 295 and 798 K. Synthetic samples of HgS were prepared by reaction
between sulphide and mercury in aqueous solution. In a subsequently dried and aged synthetic HgS
sample, heated in vacuo, there is a change from a poorly crystalline pseudocubic material into a well
crystalline cubic material in the temperature region 583�623 K. At higher temperature (748 K), there
is evidence for a partial phase transition to the high temperature hypercinnabar HgS structure. In a
neoformed synthetic sample, heated in a sealed Ti container, the initial ‘pseudocubic’ metacinnabar
phase partially transforms to a previously unknown phase (XHgS) in the temperature range 467�522
K. This phase disappears at 527 K, and the metacinnabar phase changes to a well crystalline cubic
phase; cinnabar develops at 542 K. The proportion of cinnabar continues to increase up to 647 K. Both
metacinnabar and cinnabar phases are retained on cooling. No phase transitions were observed for the
natural cinnabar sample.

Item Type:

Article

Additional Information:

University of Manchester - Daresbury Laboratory collaboration using the Daresbury Synchrotron Radiation Source.